There are a variety of bin unloading systems which utilize a centrally positioned well in the bin floor, a discharge auger for moving material from the well, and a sweep auger which moves radially about the bin floor sweeping material into the well. These systems provide an advantage when the level of material in the bin is low, as material is swept into the well and removed by the discharge auger that would otherwise have to be removed with shovels. Examples of these bin unloading systems can be found in Canadian Patents 840,857; 888,012; and U.S. Pat. Nos. 4,377,364; 4,534,693; and 4,806,058.
These bin unloading systems work extremely well. However, they can only be used in bins which have a well in their floor. This makes it difficult to convert existing bins over to this form of bin unloading system. A further example of a bin unloading device which is mounted above the floor is shown in U.S. Pat. No. 4,824,312 (Schiltz) which discloses a substantially horizontal discharge auger arranged at a height above the floor, a vertical lift auger lifting the material from the floor to the horizontal discharge auger and a sweep auger which rotates around a centre axis of the bin and pulls the material from the bin into the centre to the bottom of the vertical lift auger. This arrangement is however disadvantageous in that it does not properly communication the materials from the sweep auger into the discharge auger in a manner which provides efficiency of discharge and protects the material against damage. Furthermore it is intended that significant parts of the device are removed from each bin and transferred to a next bin. While on the face of it provides an economic arrangement, the disadvantages of having to extract the parts of the device render it less efficient.
U.S. Pat. No. 3,536,210 (Dickinson) discloses an arrangement of the underfloor type in which the sweep auger is driven by a gear box at a centre of the bin with that gear box being driven by a longitudinal shaft extending along the hollow interior of the discharge auger drive shaft. The interior shaft and the hollow shaft can be disconnected so as to drive only the discharge auger or the drive shaft can be connected to the hollow shaft to drive both the sweep auger and the discharge auger. However again this arrangement is of the underfloor type which is disadvantageous in that it requires excavation of the floor.
U.S. Pat. No. 3,647,094 (Jackson) discloses a sweep auger with a shroud having a closed front face with a number of flaps which can be opened one at a time along the length of the sweep auger.
French Patent 2,355,747 discloses an above floor arrangement of the type including a vertical lift auger, sweep auger and a discharge auger similar to that of Schlitz. The interconnection between the vertical lift auger tube and the discharge auger tube is formed simply by welding or attaching the horizontal tube of the discharge auger into one side face of the vertical tube of the lift auger. This arrangement does not allow the ability to maximize the efficiency of transfer and to ensure reduced damage of the material to be transported.